Thread-cutting die



Dec. 13, 1927. 1,652,673

w. A. JENKms THREAD CUTTING DIE Filed June 29 1925 14 Patented Dec. 13, 1927.

WILLIAM A. JENKINS, or WILMINGTON, CALIFORNIA;

THREAD-CUTTING DIE.

The present invention relates to thread cutting dies and has for its principal objects, the provision of a long-lived, etlicient (be which may be used in automatic thread. cutting machines or in lathes and the like, as well as on stocks. V

Another object ofthe invention is to provide .a die which may be repeatedly sharpened with ease andwithout exercise of par ticular skill. 1 i

In present types of dies, the die, when cutting a thread,has all possiblecutting edges and surfaces in contactwith the metal being Worked. is distributed throughout all the threads of the die, and after such a die has worn to' any appreciable degree the change or repair that can be made is to contract the die, provided it is the adjustable type. If the character. or contour of the threads change through wear or otherwise, there is nothing practical that can'be done to alter same. 7

It is therefore another object of the invention to provide a die in which all of the cuttingthreads thereof arenot used at the same time, or inother words, to provide a die in which a large area is given to threads, the major portion of which are kept in. re serve until preceding ortions have. worn sufficiently to be unfitted for use.

- Another object of the invention is to provide a die of the above character which is designed to provide the correct type of throat and to give therequired chip clearance.

Still other objects and vadvantages of my 7 invention will appear hereinafter.

"I have illustrated my invention by the accompanying drawings in which: V

Fig. 1;is a vertical section of a nipple threading machine to which one embodiment of my invention is applied.

Fig. 2 is a face View thereof.

Fig. 3 is an enlarged detail section .on a line 33 of Fig. 1.

Fig. 4 is a perspective of a die member constructed in conformance with the inven tion, said die member being adapted for use singly or in multiples as shown in Figs. 1 and 2.

Said die member, indicated throughout the drawings by the numeral 6, is made of a single circular blank or disc of suitable metal, from which disc a portion of the-metal is cut away, as at 7. The portion cut away circular disc Therefore, the wear on such a. die

Application filed June 29, 1925. Serial No. 40,244.

is segmental. The remaining part of the disc, in the embodiment illustrated, is more than 180 of a circle. but it will be apparent hereinafter that either a comparatively small segment, or a large segment may be cut away. If the removed portion is in excess of 180 of a circle, the die member will have a segmental appearance, therefore. it may be said of the die member, that it is of form with a segmental por-. tion removed, and it may also be referred'to as being segmental in itself.

In any case. said member is distinguished by an arcuate threaded perimeter 8 described around a given point. In the embodiment shown, said point is represented by a central aperture, the threaded perimeter being coaxial of the aperture. Saidmember is further distinguished by an inwardly ex-v tending surface 9 intersecting the threaded perimeter at a suitable angle to provide suitable cutting edges 10 by virtue of the abrupt terminations of the threads on said perimeter. The best angle of such intersection is believed to be about 90, in which the said surface is truly radial of the perimeter. Such angle of intersectionwprovides maximum strength with the best possible chip clearance consistent with strength, and it will be apparent hereinafter that greater chip clearance is provided by my invention, than is obtained in usual types of thread, cutting dies.

The die member illustrated is designed for cutting pipe threads or othertaper threads, and the complete embodiment shown is particularly suited for threading pipe nipples and the like. However, the invention is obviously applicableto straight-thread cut- The die is shown as provided ting purposes. with the usual throat 12 .'the threads increasing in fullness rearwardly from the throat in conformance with accepted practice.

The parts of the machine shown in Figs. 1 and 2 include a spindle 13 and a face plate 14, which may be properly associated with the spindle by suitable feeding and backingofl' mechanisms (not shown). The plate is provided with radially disposed slots 15. Said face-plate includes a circumferential, rearwardly extending wall or flange 16, carrying a plurality of studs 17 projecting radially inward and aligned with correspondin slots. Said studs are revolubly held to the wall 16 by means of integral collars 18; a

no I

smooth portion 19 of the stud being a revolving fit in a drilled hole 20 provided-in said wall.

Associated with each stud, there is a plate 21, disposed behind a corresponding slot.

, Said plate'may be moved inwardly and outlll - o'lf'rotation of IhB'IEQ'CG plate,

bodiment illustrated, for example, the com-- wardly radially of the face plate by proper turning movement of the stud. Each one of plates 21 is provided with a central aperture 22 aligned with the slot and through which a hollowfinternally threaded bolt 23 isextended. The end of each bolt extends beyond the outer-surface of the face plate.

Over each of the radial slots, one'of the die members is disposed.

plate by means of-bolt 2 L screw-threaded intovthe hollow bolt 23. The centralaperture: of each die member-is bounded by a ser rated or roughened surface 25 which: in-

sentedvon each die-member by the intersection'of the perimeter with the surface 9-, are disposedan equaldistance from the center so that the emplete nipple-threadingdie is possessed of tour cutting-edges;

Intheoperation ofthe complete die, each die member touches metal at extreme cutting edge only, the remainder of the threaded perimetercurving rearwardly' and'raway from the work to provide an ideal chip. clear ance; or space indicatedby the" numeral. 28. \Vhe'n the cutting edge ofa die member becomes Worn, or .thethread'sat the cutting edge break'or'be'come otherwise-unfitted, the

surface 9isplaced against a grinding wheel The die member is held securely contiguous with the face (not shown) and said surface is ground down until a new and untouched portion of the perimeter is in intersection with the surface 9. Thus, the dies are constantly renewable, and a. die such asshown in Fig. 2, will last many times longer than if all parts of the threads were simultaneously used, as in the case of annular dies in which the threads :are cut onian. inside perimeter. The die members are easily manufactured setting the blankina latheor the like, turning the threads and throat, and grinding thesur face 9.:

While-I have shown and described a.spe-.

cific embodiment of my invention I do not.

limit myself to any specific construction or arrangement of parts and may alter the-parts and the construction and arrangement there.- of, as I- desire, without enlarging the scope of my invention, within the appended claim.

I claim asmyinvention: V The combination with. a. plate provided with a centrally arranged opening" and. a.

series. of radially disposed slotsibetween said opening'and the edge ofsaid plate, radially adjustable blocks arranged on themear face of saidplate, which blocks overliethe radial slots, abolt carried by each. block anclzpro-v jecting slot a tioned on the front. face. of: the plate; over each radial opening; therein, a; portionof' the.

periphery of'each diebeing cutiaway'so: as

tov provide a radially" disposed surface. that intersects v at right angles the: threadedsur: face of the disk, the radially disposed sure faces of all. the. disks projecting: inwardly from the. marginal edgeoft/heiopening in. the plate,.there: being an aperture; formed. in the center of each disk'theinner' portion.

of which. aperture. is; countersunk and: corrugated, a retaining disk positioned in the aperture of each die, the edge of which disk is'inclinedandicorrugated so as to engage the.

countersunk corrugated inner portion ofthe'.

aperture, and" means lor securing each retaining disk to theend offthe' cor-responding bolt.

In testimony whereofl affix my signature. WILLIAM A. JENKINS.

tl'irough the. corresponding radial dislc shapedthreadcutting dieposi? 

